JP2002105011A - Method for producing aromatic dihydroxy compound - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing aromatic dihydroxy compounds, comprising a phenol compound with hydrogen peroxide, by which the total selectivity of the aromatic dihydroxy compounds such as a hydroquinone compound and a catechol compound on the basis of the hydrogen peroxide can be enhanced. SOLUTION: This method for producing the aromatic dihydroxy compounds, comprising reacting the phenol compound with the hydrogen peroxide in the presence of crystalline titanosilicate and a polyalkylene glycol monoether compound to produce the aromatic dihydroxy compounds.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing an aromatic dihydroxy compound, and more particularly to a method for hydroxylating phenols with hydrogen peroxide to produce a corresponding aromatic dihydroxy compound. The aromatic dihydroxy compound obtained by the method of the present invention is, for example, hydroquinone or catechol, and is useful as various organic synthetic intermediates or raw materials, and is used as a reducing agent, a rubber drug, a dye, a drug, a pesticide, a polymerization inhibitor. Used in the fields of agents, oxidation inhibitors and the like.

[0002]

2. Description of the Related Art Methods for hydroxylating phenols with hydrogen peroxide include a method of reacting phenols in the presence of divalent iron ions for a long time [Nature, 165, 401 (1950)],
Alternatively, a method using hydrofluoric acid [J. Org. Chem., 35,
4028 (1970)]. In addition, it has been reported that a method using a combination of pyrophosphoric acid and perchloric acid or an alkaline earth salt thereof is industrially useful [JP-A-3-240743 (corresponding to USP No. 524508).
6)]. However, in these conventional methods, since the catalyst to be used is uniformly dissolved in the reaction solution, it is complicated to separate the catalyst from the reaction product to isolate the target product, or to remove a highly corrosive acid. There are problems such as the necessity of a reactor of expensive material for use, and the necessity of a base for neutralization when the acid as a catalyst is discarded.

[0003] Thereafter, a method using a heterogeneous catalyst, such as crystalline titanosilicate, capable of easily separating the catalyst from the reaction system has been proposed [JP-A-1-149744 (corresponding EP No. 314582A, USP No. 5254746). ), JP-A-2-29
8350, JP-A-4-66546]. In these methods, a method using crystalline titanosilicate having an MFI structure is described, and it is sufficient to simply physically separate the catalyst from the product after the reaction, which is industrially advantageous.
When the inventors performed additional tests based on the methods described in these publications, the total selectivity of hydroquinone and catechol based on hydrogen peroxide was about 67 mol%.

Further, there is a method of hydroxylating phenols with aqueous hydrogen peroxide in the presence of a cyclic ether compound such as dioxane and crystalline titanosilicate [Japanese Patent Laid-Open No. 5-170684 (corresponding US Pat. No. 5426244). JP-A-6-263670 (corresponding USP No. 5426244), JP-A-7-2714]. The technology disclosed in these publications aims to improve the selectivity of hydroquinone by adding a cyclic ether compound. For example, the selectivity of hydroquinone based on hydrogen peroxide described in JP-A-5-170684 is Although improved to 64 mol%, the total selectivity of hydroquinone and catechol based on hydrogen peroxide is 73% in mol. Further, when the inventors conducted additional tests based on the methods described in these publications, the total selectivity of hydroquinone and catechol based on hydrogen peroxide was about 65 mol%.

[0005]

An object of the present invention is to provide a method for producing an aromatic dihydroxy compound such as hydroquinones or catechols, which can increase the total selectivity of an aromatic dihydroxy compound based on hydrogen peroxide. It is to propose a method for producing an aromatic dihydroxy compound.

[0006]

The present invention is the following method for producing an aromatic dihydroxy compound. (1) A method for producing an aromatic dihydroxy compound in which a phenol is reacted with hydrogen peroxide in the presence of a crystalline titanosilicate and a polyalkylene glycol monoether compound to produce an aromatic dihydroxy compound. (2) The method for producing an aromatic dihydroxy compound according to the above (1), wherein the polyalkylene glycol monoether compound is a monoalkylaryl ether of a polyalkylene glycol. (3) The method for producing an aromatic dihydroxy compound according to the above (1), wherein the polyalkylene glycol monoether compound is polyethylene glycol mono-4-octylphenyl ether. (4) 10 parts by weight of the polyalkylene glycol monoether compound is added to 100 parts by weight of the crystalline titanosilicate.
The above (1) to be added so as to be 200 parts by weight.
The method for producing an aromatic dihydroxy compound according to any one of (3).

The phenol used as a starting compound in the present invention means unsubstituted phenol and substituted phenol. Here, the substituted phenol may be, for example, an alkylphenol substituted with a linear or branched alkyl group having 1 to 6 carbon atoms such as a methyl group, an ethyl group, an isopropyl group, a butyl group, a hexyl group, or a cycloalkyl group. it can.

Specific examples of phenols include phenol, 2-methylphenol, 3-methylphenol, 2,6-dimethylphenol, 2,3,5-trimethylphenol, 2-ethylphenol, and 3-isopropylphenol. , 2-butylphenol and 2-cyclohexylphenol, among which phenol is particularly preferred. When a compound having substituents at both the 2- and 6-positions of the phenol is used, the aromatic dihydroxy compound to be produced is only a hydroquinone derivative.

The composition of the crystalline titanosilicate used as a catalyst in the present invention may be any structure having the structure represented by (SiO ₂ ) x · (TiO ₂ ) _(1-x) . In this case x
The value of / (1-x), that is, the atomic ratio of Si / Ti is not particularly limited, but is preferably 5 to 1000, and more preferably 10 to 500. The crystalline titanosilicate is preferably an MFI-type crystalline titanosilicate having an MFI structure.

The crystalline titanosilicate can be produced by a known method. For example, by preparing a reaction mixture consisting of a silicon source, a titanium source, a nitrogen source, and water,
It can be produced by hydrothermal synthesis. Examples of the silicon source include alkoxides of silicon and colloidal silica. Examples of the titanium source include alkoxides of titanium, titanium halides, titanic acid, and titanium sulfide. Examples of the nitrogen source include nitrogen-containing compounds such as quaternary ammonium salts such as tetrapropyl ammonium salt and tetrabutyl ammonium salt.

The following method can be exemplified as a specific method for producing crystalline titanosilicate. The silicon source, titanium source, nitrogen source, and water are mixed while appropriately adjusting the pH to obtain a gel-like precipitate. 100-
Hydrothermal synthesis under heating at 250 ° C. for 1 to 100 hours to obtain a solid product. This solid product is washed with deionized water,
Then, after drying, the crystalline titanosilicate can be obtained by firing at a temperature of 400 to 600 ° C. in the air. In such a production method, when a tetrapropylammonium salt is used as a nitrogen source, crystalline titanosilicate having an MFI structure can be easily obtained.

A method for producing crystalline titanosilicate is disclosed in JP-A-56-97720 (corresponding US Pat.
For example, crystalline titanosilicate produced according to these methods can be used. A commercially available crystalline titanosilicate can also be used. In addition, if x / (1-x) is within a predetermined range, the MFI-type crystalline titanosilicate may also be used.
Commercial products can be used.

In the present invention, specific examples of the polyalkylene glycol monoether compound used as a catalyst together with the crystalline titanosilicate include polyethylene glycol mono-4-octylphenyl ether and polypropylene glycol mono-4-octylphenyl ether. , Polyethylene glycol monomethyl ether, polyethylene glycol monoethyl ether, polyethylene glycol monobutyl ether, polyethylene glycol monooctyl ether, polyethylene glycol monophenyl ether, polyethylene glycol mono-4
-Methylphenyl ether, polyethylene glycol mono-4-butylphenyl ether, polyethylene glycol mono-4-nonylphenyl ether and the like. Especially among them, polyethylene glycol-
4-octylphenyl ether is preferred.

The polyalkylene glycol portion of the polyalkylene glycol monoether compound used preferably has a molecular weight of about 88 to 880, more preferably 2 to 880.
20 to 660.

The polyalkylene glycol monoether compound used in the present invention is preferably used in a mixture with water. For example, when polyethylene glycol-4-octylphenyl ether is used, the ratio of ether / water (weight ratio) is preferably 1/10 to 1/1000, particularly preferably 1/30 to 1/200.

In the production method of the present invention, an aromatic dihydroxy compound is produced by reacting a phenol as a raw material compound with hydrogen peroxide using the above-mentioned crystalline titanosilicate and polyalkylene glycol monoether compound as a catalyst. In the production method of the present invention, the total selectivity of the aromatic dihydroxy compound, which is a reaction product, based on hydrogen peroxide can be increased.

The polyalkylene glycol monoether compound used as the catalyst has a polar hydroxyl group at the terminal and a nonpolar alkyl group. Since the polyalkylene glycol monoether compound is adsorbed on the surface of the crystalline titanosilicate from the polar hydroxyl group side and the polarity of the surface of the crystalline titanosilicate changes, the total selectivity increases due to the micelle effect. Conceivable.

Specific examples of the aromatic dihydroxy compound as a reaction product include hydroquinone, catechol, 2-methylhydroquinone, 3-methylcatechol,
4-methylcatechol, 3-methylhydroquinone, 1,
4-dimethylhydroquinone, 1,4-dimethylcatechol, 3,5-dimethylcatechol, 2,3-dimethylhydroquinone, 2,3-dimethylcatechol, 1,2,4
-Benzenetriol, 4,4'-dihydroxyphenyl ether, isopropyl-4-hydroxyphenol and the like.

The reaction temperature is in the range of 30 to 130 ° C., preferably 40 to 100 ° C. 30
When the temperature is in the range of -130 ° C, the time until the added hydrogen peroxide solution is burned off and the reaction is completed is short, and the productivity is increased. Further, the yield of the reaction product tends to increase. The reaction time is desirably 0.5 to 5 hours, preferably 1 to 3 hours. The reaction pressure is not particularly limited.

The reaction may be carried out batchwise or continuously. In the case of performing continuously, it may be performed in a suspension type uniform mixing tank, or may be performed in a fixed bed flow type plug flow type. Further, the reaction product may be recycled and used again as a reaction raw material.

The amount of the crystalline titanosilicate used is 0.5 to 3 based on 100 parts by weight of the starting compound (reaction mixture).
It is desirably 0 parts by weight, preferably 1 to 20 parts by weight. When used in the range of 0.5 to 30 parts by weight, the time required for the added hydrogen peroxide to disappear and the reaction to be completed is short,
High productivity.

The amount of the polyalkylene glycol monoether compound used depends on the amount of the crystalline titanosilicate 1 as a catalyst.
It is desirably 10 to 200 parts by weight, preferably 25 to 100 parts by weight, based on 00 parts by weight. 1 usage
When the amount is 0 part by weight or more, the effect of the present invention in which the total selectivity of the aromatic dihydroxy compound is increased by the addition of the polyalkylene glycol monoether compound is clearly exhibited.
Although the use amount may be more than 200 parts by weight, the use amount is preferably 200 parts by weight or less from the economical point of view because the recovered amount of the polyalkylene glycol monoether compound after the production increases.

The amount of hydrogen peroxide to be used is desirably 0.5 mol or less, preferably 0.3 mol or less, per 1 mol of phenol as a raw material compound. Hydrogen peroxide is usually used as a hydrogen peroxide solution, but its concentration is not particularly limited, and a normal aqueous solution of about 30% by mass may be used, or a high-concentration hydrogen peroxide solution may be used in the reaction system. It may be used after diluted with an active medium. Examples of a medium used for dilution include acetonitrile, ethanol, methanol, water and the like. When a reaction medium is used, its use amount is not particularly limited, but is usually 10 to 200 parts by weight, preferably 20 to 200 parts by weight, based on 100 parts by weight of the starting compound.
It is desirable to use 150 parts by weight.

The aromatic hydroxy compounds such as hydroquinone and catechol thus obtained are useful as various organic synthetic intermediates or raw materials, and are used as reducing agents, rubber drugs, dyes, drugs, agricultural chemicals, polymerization inhibitors, oxidation inhibitors, and the like. It is used in fields such as inhibitors.

[0025]

As described above, according to the present invention, when a corresponding aromatic dihydroxy compound is produced by reacting a phenol with hydrogen peroxide using a crystalline titanosilicate, a polyalkylene glycol monoamine is produced. By performing the reaction in the presence of an ether compound, the total selectivity of aromatic dihydroxy compounds such as hydroquinones and catechols based on hydrogen peroxide can be improved.
Therefore, it is possible to avoid the useless waste of the raw material compound, and it is possible to effectively use the raw material compound part.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be further described with reference to specific examples, but the present invention is not limited thereto. Example 1 A 100-ml three-necked flask equipped with a cooler, a thermometer, a dropping funnel, and a magnetic stirrer chip,
0.434 g of titanosilicate (TS-1) catalyst, 4.34 g of phenol, polyethylene glycol mono-4-
Octyl phenyl ether (molecular weight of PEG = 44
0) 0.216 g and 20 g of water were charged and heated to 50 ° C. in a water bath while stirring with a stirrer. Where 3
1.0 ml of 0% hydrogen peroxide solution was added. After 2 hours, the reaction was stopped. After cooling the reaction solution, the catalyst was separated by filtration and a part of the reaction solution was taken. The remaining hydrogen peroxide was quantified by iodometry, and the remaining phenol and products were quantified by gas chromatography.

As a result, the conversion of phenol was 14.7.
Mol%, the conversion of hydrogen peroxide was 74.7 mol%. The selectivity of hydroquinone and catechol based on phenol was 54 mol% and 38 mol%, respectively.
The selectivities of hydroquinone and catechol based on hydrogen peroxide were 48 mol% and 34 mol%, respectively, and the total selectivity of hydroquinone and catechol was 82%.

Comparative Example 1 In Example 1, polyethylene glycol mono-4-
The reaction was carried out in the same manner as in Example 1 except that octylphenyl ether was not used. As a result, the conversion of phenol was 13.6 mol%, and the conversion of hydrogen peroxide was 72.0 mol%.
Mole%. The phenol-based selectivities of hydroquinone and catechol are 46 mol% and 33 mol%, respectively.
Met. The selectivities based on hydrogen peroxide of hydroquinone and catechol were 39 mol% and 28 mol%, respectively, and the total selectivity of hydroquinone and catechol was 67 mol%.

Comparative Example 2 A reaction was carried out in the same manner as in Example 1 except that 4 g and 6 g of dioxane and water were used instead of the mixture of polyethylene glycol mono-4-octylphenyl ether and water. As a result, the conversion of phenol was 18.4 mol%, and the conversion of hydrogen peroxide was almost 100 mol%.
The selectivity of hydroquinone and catechol based on phenol was 71 mol% and 10 mol%, respectively. The selectivity based on hydrogen peroxide of hydroquinone and catechol was 57 mol% and 8 mol%, respectively, and the total selectivity of hydroquinone and catechol was 65 mol%.

Comparative Example 3 A reaction was carried out in the same manner as in Example 1 except that 7 g and 3 g of ethylene glycol dimethyl ether and water were used instead of the mixture of polyethylene glycol mono-4-octylphenyl ether and water. As a result, the conversion of phenol was 16 mol%, and the conversion of hydrogen peroxide was 99 mol%. The selectivities of hydroquinone and catechol based on phenol were 54 mol% and 38 mol%, respectively. The selectivities based on hydrogen peroxide of hydroquinone and catechol were 39 mol% and 19 mol%, respectively, and the total selectivity of hydroquinone and catechol was 58 mol%.

Claims (4)

[Claims] 1. A method for producing an aromatic dihydroxy compound, comprising reacting a phenol with hydrogen peroxide in the presence of a crystalline titanosilicate and a polyalkylene glycol monoether compound to produce an aromatic dihydroxy compound. 2. The method for producing an aromatic dihydroxy compound according to claim 1, wherein the polyalkylene glycol monoether compound is a monoalkylaryl ether of a polyalkylene glycol. 3. The method for producing an aromatic dihydroxy compound according to claim 1, wherein the polyalkylene glycol monoether compound is polyethylene glycol mono-4-octylphenyl ether. 4. The polyalkylene glycol monoether compound is added in an amount of 10 to 200 parts by weight based on 100 parts by weight of the crystalline titanosilicate.
4. The method for producing an aromatic dihydroxy compound according to any one of claims 1 to 3.